the catapult/trebuchet project

Post by **Triton** » Mon Oct 10, 2005 8:48 pm

in my tech physics class in school (its basically a shop class with math in it lol) we are haveing a competition to build "pumpkin chunkin" devices, trebuchets, slingshots etc and i will have pics of our machine and hopefully a video of it throwing, we are using a trebuchet style machine with a garage door spring for power, the arm is 8' total with 2' give or take on the spring side of the fulcrum, it uses a sling as well and is VERY powerful in its movenments! at first when we test threw the projectile (a normal pop bottle full of water) would go straight up very far, about 50-60foot, we outthrew our competitors...in the wrong direction, the other 2 teams that have thrown so far have shot about 55-65 foot, our best throw so far (today) was roughly in the area of 150-180 foot!, the sling helped big time, my goal is 250 or 300 feet. i will try and put some pics up later, and mebe a test vid if i can get a camera

Weebl · Post by **Weebl** » Mon Oct 10, 2005 9:11 pm

Very nice, I built a trebuchet last year for Science Olympiad competition, and that was sure hard. I assume you didn't use counter-weights, relying on the spring to hurl the projectiles. I'm impressed by the distance you got, I'd love to see a video of that, or pictures of the catapult itself.

Post by **Sparkfist** » Mon Oct 10, 2005 9:25 pm

Just to clear things up a catapult is a general term for all siege engines, a Trebuchet is a couter-weight siege engine. I like them just because of the fact that they are great works of art in just making one and further they are capible of destrution!

Dont know if anyone you would but the movie Kindom of Heaven has trebs used so its something to watch if you want to see the power of those things.

As for anyone interested in looking at some siege weapons. Siege-engine.com is a good site. There is also Trebuchet.com, they sell kits and even have a section for howtos so you can have a guide to make your own.

nos_slived · Post by **nos_slived** » Mon Oct 10, 2005 9:47 pm

I scream combustion powered pumpkin shooters.

Post by **Sparkfist** » Mon Oct 10, 2005 9:51 pm

nos_slived wrote:I scream combustion powered pumpkin shooters.

Combustion is overrated, use compressed air. Have you any idea how much power is contained in those SCUBA tanks? More then you think.

nos_slived · Post by **nos_slived** » Mon Oct 10, 2005 11:48 pm

Compressed air is good for some things, but has it's problems. It's a lot easier to make a combustion powered shooter, because the trigger works better in most cases. Also, gases for combustion are cheaper than SCUBA tanks.

Foxx373 · Post by **Foxx373** » Tue Oct 11, 2005 1:02 am

I bult a trebuchet once, for the sole purpose of hurling small animals into traffic. I also built combustion and pnumatic guns. I had a pnumatic sniper rifle shoot arrows with explosive heads at stuff. I live in a city area, and all i can say is some poor butthole has some serious holes punched into the side of their house and car. ... and the poop egress i shot in the nuts ith a .25 pound solder 3/4" diameter slug.

Sounds like a fun class!!! Most of my highschool classes sucked, especially cause the banned me from gym, study hall, machine shop, and chemistry.

Pneumatic is a LOT easier to calculate its trijectory rather than the chaotic behavior of combustion based systems.

Post by **Black Six** » Tue Oct 11, 2005 5:36 am

My friends and I started building a trebuchet over the summer, but with vacations and jobs and such we never got it finished; we're hoping to work on it when we all go back home for Thanksgiving. It's about 5' tall and will has a 6' throwing arm.
Weebl, you do/did Science Olympiad too? I did that from 6th grade until my senior year, I loved that club, a couple of my friends built a trebuchet for it once (that's where we got our idea to make a larger one) and I ended up helping with some of the testing and fine-tuning. Fun stuff!

Post by **Triton** » Tue Oct 11, 2005 6:28 am

hey nos, you would be impressed by compressed air if you saw some of the guns people made on that pumpkin chunkin show on tlc or whatever, a range of about 4000 feet!!!!!

Post by **Sparkfist** » Tue Oct 11, 2005 9:30 am

nos_slived wrote:Also, gases for combustion are cheaper than SCUBA tanks.

Rent a SCUBA tank, and refilling it should cost no more then $2-4. I've read about combustion they generate what maybe 25psi at the most? Though a SCUBA tank is the extreme with an average of 3000psi at full, you can do more with compressed air. Why do you think car's engines compress the fuel-air mix to get better power out of it. Though I wouldnt follow the idea that internal compusion engines use unless you make the cylindar out of a solid pipe and even then dont go nuts.

I think if I can get my hands on some 2x4s I'd try seeing about making a billista or treb again.

Post by **Triton** » Tue Oct 11, 2005 10:09 am

did test shots with the fixed sling today, average about 175-180 best today 198!

nex try with 2 springsd and a further improved sling

nos_slived · Post by **nos_slived** » Tue Oct 11, 2005 11:39 am

Triton wrote:hey nos, you would be impressed by compressed air if you saw some of the guns people made on that pumpkin chunkin show on tlc or whatever, a range of about 4000 feet!!!!!

I've made compressed air guns, but they usually don't work as well as a really good combustion gun. With combustion you have to be extremely accurate with the measurements, but get awesome power is made right. The problem with compressed air is getting a trigger that can release fast enough to utilise the full pressure.

Post by **benheck** » Tue Oct 11, 2005 4:33 pm

Make it a RAIL GUN pumpkin shooter!

That's the future, man!

-Ben

Post by **gannon** » Tue Oct 11, 2005 4:49 pm

umm... would the pumpkin even survive until the end of the barrel with a rail gun?

Post by **bicostp** » Tue Oct 11, 2005 5:00 pm

Well, on a smaller scale, I've built:

-A pen blowgun from G-force's plans
-A cap grenade (Just uses cap gun caps to make a BANG noise)
-An acorn sling (When I was a kid we had acorn wars all over the neighborhood.

Good times.)

I want to build:

-A Chap-Stick dart gun (from <a href="http://www.i-mockery.com/minimocks/chap ... php">these directions on i-mockery.com</a>

)

DISCLAIMER: Neither I nor i-mockery nor G-force are responsible for injuries suffered due to misuse of homemade dangerous toys. bicostp would like to let you know that he wouldn't ever use these things against anyone. (That's what the rat-flail's for ;P)